Linux Basic Commands

Linux Basic Commands 

For changing directory / to /etc

[root@pc1 /]# cd /etc

One step back /etc to /

[root@pc1 etc]# cd ..

Go to previous working directory

[root@pc1 /]# cd -

Go to current login user home directory

[root@pc1 etc]# cd ~

Show the contents of /etc in single color

[root@pc1 ~]#  dir  /etc

Show the contents of /etc in different colors with nature of contents

[root@pc1 ~]#  Ls  /etc

create a folder on root partition

[root@pc1  ~]#  mkdir  /disk

Create a folder in /disk

[root@pc1  ~]#  mkdir  /disk/dir

Create multiple folder in multiple directories with single command

[root@pc1  ~]#  mkdir  /etc/dir1 /var/dir2 /usr/dir3

Create multiple folder in same directory

[root@pc1  ~]#  mkdir  dir1 dir2 dir3

Copy a file in directory

[root@pc1  disk]#  cp  file dir

Copy a file from /disk/file and paste it in /disk/dir/

[root@pc1  disk]#  cp  /disk/file /disk/dir

Copy a directory with –r option

[root@pc1  disk]#  cp  -r  dir  dir2

Copy a file from /disk/file and paste it in /etc with myfile name

[root@pc1  disk]#  cp  /disk/file  /etc/myfile

Remove a file

[root@pc1  disk]#  rm file

Remove a file with forcefully option

[root@pc1  disk]#  rm –f  file

Remove a directory with out –r option and you face will an error

[root@pc1  disk]#  rm dir

Remove a directory with –r option

[root@pc1  disk]#  rm  -r  /disk

Remove a directory with forcefully option

[root@pc1  disk]#  rm  -rf  dir

Move /etc/dir1 to /disk/ with different name

[root@pc1  disk]#  mv  /etc/dir1  /disk/mydir

Rename the folder name mydir to dir

[root@pc1  disk]#  mv  /disk/mydir  /disk/dir

Rename the file name with myfile

[root@pc1  disk]#  mv file myfile

Read a file page by page with less command

[root@pc1  disk]# less  /etc/grub.conf

Read a file page by page with more command

[root@pc1  disk]# more  /etc/qrub.conf

Read first ten lines of grub.conf

[root@pc1  disk]# head  /etc/grub.conf

Read last ten lings of grub.conf

[root@pc1  disk]# tail  /etc/grub.conf

Read first 12 lines with –n option

[root@pc1  disk]# head  -n  12  /etc/grub.conf

Read last 11 lines with –n option

[root@pc1  disk]# tail  -n 11  /etc/grub.conf

Copy the contents of /etc/grub.conf in /disk/file

[root@pc1  disk]# cat  /etc/grub.conf > /disk/file

Append the contents /etc/mtab in /etc/file

[root@pc1  disk]# cat  /etc/mtab >>  /disk/file

Merging tow commands with pipe sign output of the first command is input of second command

[root@pc1  disk]# cat  /etc/squid/squid.conf I more

Count the total lines of squid.conf

[root@pc1  disk]# cat  /etc/squid/squid.conf I wc  -L

Show only spool words in squid.conf

[root@pc1  disk]# cat  /etc/squid/squid.conf  I grep  spool

Flush the contents of file

[root@pc1  disk]# cat  /dev/null  >  /var/log/messages